Peritoneal macrophages from adjuvant arthritic rats enhance tumour cell growth in vitro

Human bronchoalveolar macrophage cytotoxicity for cultured human lung-tumour cells

Human bronchoalveolar macrophages were separated from other free lung cells by density sedimentation on Percoll gradients. They were then tested for cytotoxicity against the human lung adenocarcinoma cell line A549, using a Selenomethionine-75 post-labelling assay. The cytotoxicity of the macrophages increased as the effector:target cell ratio was increased, approaching 100% at 20:1. There was no significant difference in the cytotoxicity of macrophages isolated from the lungs of bronchial-carcinoma or non-carcinoma patients. The highly cytotoxic nature of the macrophages was not due to selection of a more potent cytotoxic subpopulation of macrophages on the Percoll gradient, nor to a generally elevated activation of the macrophages due to the pathological conditions in the patients' lungs. An attempt to determine whether low concentrations of macrophages could potentiate target-cell growth proved negative. Cytotoxicity of macrophages for cultured lung target cells was not restricted to A549 cells and is not in accordance with the view that defective bronchoalveolar macrophage cytotoxicity contributes to the emergence of bronchial neoplasia.

Antirheumatic drugs and macrophage function: effects on tumour cell growth in vitro

The ability of the antirheumatic drugs D-penicillamine, chloroquine and levamisole to modify macrophage-mediated inhibition of tumour cell growth in vitro was investigated. Increasing numbers of rat peritoneal macrophages were cocultured with a fixed number of ascites hepatoma AH-13 rat tumour cells. Tumour cell growth was assessed as the uptake of 3H-thymidine (3H-TdR) by AH-13 cells at the end of a 24 h period of coculture with macrophages treated in vitro or in vivo with the various drugs. In vitro, preincubation of macrophages with D-penicillamine or chloroquine (50 - 250 micrograms/ml) increased tumour cell 3H-TdR incorporation, compared to cultures with untreated macrophages. Macrophages from rats treated with D-penicillamine or chloroquine (50 mg/kg/day orally) for 4 days similarly increased tumour cell 3H-TdR incorporation, compared to cultures with macrophages from untreated rats. These effects persisted for at least 3 to 4 weeks of treatment. Preincubation with levamisole (10 - 100 micrograms/ml) in vitro had no effect on macrophage-mediated inhibition of tumour cells, whereas increased tumour cell 3H-TdR incorporation was observed in cultures with macrophages from rats treated with levamisole (5 mg/kg/day orally) in vivo. Macrophages from rats with experimentally induced chronic inflammation, i.e. adjuvant arthritis, were found to increase tumour cell 3H-TdR incorporation, compared to macrophages from nonarthritic rats. This trend was further enhanced by treatment with D-penicillamine, chloroquine or levamisole.